Conventionally, a large number of studies have been made of saccharides from cereals. Particularly with respect to starch, there are an overwhelming number of reports relating to its major components i.e., amylose and amylopectin after the epoch-making results of the study on starch made by K. H. Meyer in 1940. According to Jiro Nikuni ("Denpun Kagaku Handbook" (Starch Science Handbook), compiled by Jiro Nikuni and published in 1977 by Asakura Shoten K. K., Japan), starch manufacturing industry developed thereafter is also an industry which has been developed basically following their results.
Meanwhile, it has been revealed that a substance called glycogen, which is similar to starch amylopectin, is present in an animal body and serves as an important energy source, as described in a method for experiment on starch-related saccharides ("Seikagaku Jikkenho" (Experimental Method in Biochemistry), vol. 19, page 22, published in 1986 by Gakkai Shuppan Center, Japan). However, as is also reported by Nakamura Y. et al. (PHYSIOLOGIA PLANTARUM, 97, 491-498 (1996), Denmark), the presence of a plant glycogen-like substance is suggested by using special experimental products such as corn (unmatured seeds), corn starch mutant species (e.g. sugary species and amylose extender species), and rice starch mutant species (the same mutant species as above). However, the presence of such a substance for rice serving as a usual common food is not known so far, and as a matter of fact, the industrial application of such a substance has not been made.